Since there seems to be quite some demand for tinfoil hats (see especially in the Residents' Answers and Employment subforums, or generally anywhere where gambling is mentioned), I have made a simply one. It's for free in front of my "shop" (actually just a small building with a few pictures and pieces of furniture) at Blackmount 201, 64, 81.
It attaches to the chin (so that nekos, etc. might wear it, too) and comes with full permissions. Since it's a cone-shaped tinfoil hat, it doesn't do anything useful but sit on your head and clutter your inventory.